This general guide will help to explain to you some of the concepts and terms used in relation to Canon EOS flash photography.
Strobe and Flash.
The main differences between a strobe and a flash are the use of terminology according to UK or US English. In the US, a strobe is a flash unit whereas in UK a strobe refers to anything emitting blinking lights. Another confusion in terms is the between "Speedlight" and "Speedlite". Both are trade names of Nikon and Canon respectively used for their series of flash units.
Guide Number
The maximum distance which a flash unit can reach with its flash pulse is known as the guide number. But if you are using automatic flash metering, this number is not important at all. You will only need to know this number when you are more inclined to do manual settings for your flash.
EV (Exposure Value)
EV or Exposure value is the value used for deciding the sensitivity of the AF (Auto Focus) system or exposure metering which respect to film types or lenses. You need to combine the aperture and shutter speed together to get this value. For example, 1/125 and F2 is equal to EV9 which is also equivalent to F4 and 1/30.
Dedicated and Non Dedicated Flash Units
Most Camera manufacturers also manufacture their own line of flash units to complement their camera models. These "own" brand of flash units are known as dedicated flash units. The Canon line of flash units is known as the Speedlite series. They are able to work together with the camera proprietary system to give more precision photography. Non dedicated Flash units are those flash units which are manufactured by third party manufacturers. Usually generic in nature, they cannot communicate with the camera proprietary system.
Shoe Mount
Usually located on the top mirror or prism housing, the shoe mount is a slide-in rectangular socket meant for attaching an external flash unit to the camera. They are also known as "Hot Shoe Mount" as they possess an electrical circuit which will initiate the flash unit once it is attached to the camera. Canon EOS cameras have an additional four electrical points in the shoe mount which transmit data from the flash trigger.
Redeye Effect
When the light from a flash unit is reflected back into the camera off the walls of the retina, this will produce the Redeye effect which we always see in pictures taken in low ambient light conditions. This due to the fact that the low ambient light condition causes the pupils of the eyes to dilate bigger and the color red is because the retina walls are lined with red blood vessels.
Redeye Reduction
To reduce the problem of Red Eye, one can use several methods. The most effective way is to distance the flash away from the lens or bounce the flash light onto the subject as opposed to flashing directly at the subject. The other way is for the subject to observe a bright light source just before taking the subject picture. This will make the pupils smaller and thus lessening the reflective capability of the retina. - 16003
Strobe and Flash.
The main differences between a strobe and a flash are the use of terminology according to UK or US English. In the US, a strobe is a flash unit whereas in UK a strobe refers to anything emitting blinking lights. Another confusion in terms is the between "Speedlight" and "Speedlite". Both are trade names of Nikon and Canon respectively used for their series of flash units.
Guide Number
The maximum distance which a flash unit can reach with its flash pulse is known as the guide number. But if you are using automatic flash metering, this number is not important at all. You will only need to know this number when you are more inclined to do manual settings for your flash.
EV (Exposure Value)
EV or Exposure value is the value used for deciding the sensitivity of the AF (Auto Focus) system or exposure metering which respect to film types or lenses. You need to combine the aperture and shutter speed together to get this value. For example, 1/125 and F2 is equal to EV9 which is also equivalent to F4 and 1/30.
Dedicated and Non Dedicated Flash Units
Most Camera manufacturers also manufacture their own line of flash units to complement their camera models. These "own" brand of flash units are known as dedicated flash units. The Canon line of flash units is known as the Speedlite series. They are able to work together with the camera proprietary system to give more precision photography. Non dedicated Flash units are those flash units which are manufactured by third party manufacturers. Usually generic in nature, they cannot communicate with the camera proprietary system.
Shoe Mount
Usually located on the top mirror or prism housing, the shoe mount is a slide-in rectangular socket meant for attaching an external flash unit to the camera. They are also known as "Hot Shoe Mount" as they possess an electrical circuit which will initiate the flash unit once it is attached to the camera. Canon EOS cameras have an additional four electrical points in the shoe mount which transmit data from the flash trigger.
Redeye Effect
When the light from a flash unit is reflected back into the camera off the walls of the retina, this will produce the Redeye effect which we always see in pictures taken in low ambient light conditions. This due to the fact that the low ambient light condition causes the pupils of the eyes to dilate bigger and the color red is because the retina walls are lined with red blood vessels.
Redeye Reduction
To reduce the problem of Red Eye, one can use several methods. The most effective way is to distance the flash away from the lens or bounce the flash light onto the subject as opposed to flashing directly at the subject. The other way is for the subject to observe a bright light source just before taking the subject picture. This will make the pupils smaller and thus lessening the reflective capability of the retina. - 16003
About the Author:
Tim Harris is a canon camera enthusiast. For tips on choosing and buying cameras, do check out Canon OS Camera website. Camera 40D Digital Rebel XTI 3D Blog
